Folding machine roller adjusting mechanism



May 14, 1963 V N. c. BROOKS FOLDING MACHINE ROLLER ADJUSTING MECHANISM Original Filed April 15, 1959 Norman C. Brook:

INVENTOR.

ATTOR/Vf) United States Patent 3,089,695 FOLDDJG MACHENE ROLLER ADJUSTENG MECHANESM Norman C. Brooks, Austin, Tex., assignor, by mesne assignments, to Miehle-Goss-Dexter, Inn, Pearl River, N.Y., a corporation of Delaware Continuation of application Ser. No. 806,537, Apr. 15, 1959. This application Nov. 7, 196i), Ser. No. 124,741 15 Claims. (Cl. Mil-68) This invention relates to folding machines, and more particularly to mechanisms for use in such machines in the adjusting of the rollers thereof.

This application is a continuation of my copending application Serial Number 806,537 filed April 15, 1959 for Folding Machine Roller Adjusting Mechanism, now forfeited.

A common type of paper folding machine employs a plurality of cylindrical rollers arranged in parallel rela tionship with each other, pairs of the rollers making pressure contact with each other but being capable of being moved apart significant distances as paper passes therebetween. Paper of varying thickness and stiffness and varying numbers of sheets are fed between the rollers to effect folding, and the rollers are therefore adjustable one with respect to another, such that the proper pressure as between each pair of rollers can be established and maintained for each folding job.

In folding machines of this type, as heretofore commonly constructed, the rollers are mounted at their ends on pivotally supported levers each of which is provided with an adjustable spring whereby the pressure exerted by one roller upon another may be adjusted as desired by adjustment of the springs.

The successful operation of folding machines of this kind requires that the pressure exerted by the rollers must be uniform throughout the lengths of the rollers. Substantial variation in pressure between the ends of the rollers results in the production of imperfect folds and necessitates re-adjustment of the rollers.

Roller adjusting mechanisms of the spring type present the disadvantage of being difficult to readjust for different weights or thicknesses of paper, each readjustment usually causing substantial spoilage during trial and error adjustment of perhaps ten springs all of whose forces relate to each other. In fact, any form of ten separate adjustments is inefiicient by comparison with one adjustment.

Further, even after an adjustment has been made, the machine tends to get out of adjustment as a result of temperature variations and set taken on by the springs affecting the forces produced by the springs.

Each roller is driven by a gear, the group of which make up a gear train at one end only of the rollers. The operation of the gears under load is such as to impart a thrust upon each gear and thereby upon one end of the roller, which thrust tends to separate the rollers at one end only. For most eflicient operation the adjustment means must permit adjustment for this factor.

Springs for the spring biased roller machines are naturally selected for typical average weights of paper, and they are therefore too stiff for the fine pressure adjustments that must be made to handle onion skin and other very light weight papers without excessive spoilage. Also, the difficulty of making a number of adjustments each individually, particularly a number of related adjustments of springs, makes unfeasible the handling of many small jobs, because the adjustment takes so long and necessitates the spoilage of many sheets during the adjusting.

Further, springs inherently have spring rates, Le, a change in force with a change in degree of compression or tension. In the folding machines of the type here of interest, which fold as many as several hundred sheets per minute with perhaps four folds, the rollers tend to heat and an end of a roller slightly out of adjustment and subject to excessive pressure, tends to expand, thereby pushing the spring a bit further. Since the spring urges with a great force when compressed further, an even higher pressure is created, which means that the system inherently amplifies with the passage of time during use the errors of the operator in setting up the original adjustment.

It is further a characteristic of spring biased roller machines that the rollers tend to bounce during high speed operation as folds enter and leave the rollers, and the characteristics of the springs is to foster rather than inhibit such bouncing.

Accordingly, an object of this invention is to provide improved means for controlling the pressure and for adjusting the pressure of one roller upon another in a folding machine, by which means the disadvantages and defects mentioned above are overcome.

Another object of this invention is to provide a roller pressure control mechanism which is relatively unaffected by heating of the rollers during operation and by which substantially constant roller pressure is obtained even when the rollers are moved to ditferent positions by paper passing therebetween.

A further object of the invention is the provision of a roller adjustment mechanism by which the relationship of pressure of given pairs of rollers with respect to other pairs can be once determined, and then further adjustments of pressure of all the rollers can be made with one simple and quickly made adjustment without the need of individual adjustment of each roller or each end of any single roller.

Still another object is to provide an improved roller pressure mechanism by which equal forces can be maintained on both ends of a roller in spite of movement of the axes of the rollers as paper passes therethrough.

Still a further object is to provide an improved roller pressure mechanism wherein roller movement and oscillation is automatically dampened without alfecting or changing roller pressure.

Yet another object is to provide a mechanism by which adjustment on the various rollers can all be made simultaneously.

Yet a further object is to provide a mechanism by which the pressure of rollers, one against another, is not materially affected by the change of position of the roller as it is moved by paper being folded.

Other objects are apparent from the following description and accompanying drawings.

These objects are accomplished in accordance with this invention by the provision of a single hydraulic systerm, in which pressure is applied from the single system to each end of the various rollers with the amount of pressure determined by a single master control.

FIGURE 1 is a pictorial schematic view of a group of six rollers with accompanying guide plates and stops such as are used in typical folding machines of the type to which this invention is applied as an improvement.

FIGURE 2 is an end elevational view of the roller train of FIGURE 1, showing the manner in which the pressure adjusting mechanism of the invention is applied thereto.

FIGURE 3 is in part a sectional view taken along the line 3-3 and illustrating also in schematic form the errtire hydraulic system. I

FIGURE 4 is a vertical cross-sectional view of an alternative embodiment of the hydraulic pressure applying means or master cylinder of the invention.

Folding machines can be understood by reference to FIGURE'l wherein a train of rollers 1, 2, 3, 4, 5 and 6 are illustrated, roller 1 being the pull-in roller, roller 2 being the power roller, rollers 3, 4, and 6 being the first fold, the second fold, the third fold and fourth fold rollers, respectively.

A train of gears 7, connects each roller to the others, so that when the gear on one end of the power roller is driven, it in turn drives all the rollers to rotation at the same speed so that there is no slipping of roller faces with respect to each other.

Preferably, the surfaces of the rollers are knurled, as with slightly helical grooves.

As appears in the drawings, the various rollers are arranged with axes parallel, each rollers surface being tangent to the surface of an adjacent roller in a line. The axes of rollers 1, 3 and 5 are in one plane, and of rollers 2, 4 and 6 in another.

In such a machine paper guide and stop means are also used. Preferably one such guide and stop means may take the form of a pair of plates 1tl11 disposed between roller 1 and roller 2 and extending away from the rollers at a large acute angle to the plane containing rollers 1, 3 and 5. A plurality of adjustable stop means 3.2 are disposed between the plates 1t and 11.

In operation paper is feed between the pull-in roller 1 and the power roller 2 and into the slot defined by plates 10 and 11 until the edge of the paper meets the stops 12. The paper being thereby precluded from further passage into the space between the plates 10 and 11, a fold forms outside the lower edge of the plates ltd-11, which fold is picked up by the rollers 2 and 3 and drawn therebetween. Such a piece of paper with the fold just being formed is illustrated in FZGURE 1 at 13. Additional pairs of plates 1415 with stops 16, 171'& with stops 19, and 2tl21 with stops 22 are positioned in locations with respect to other pairs of rollers, similarly to the plates 1011 with respect to rollers 1 and 2. Thus, paper with one fold therein passing between rollers 1 and 2, moves into the slot between the plates I4-15 until it meets stops 16, and a fold is then formed which leads through between rollers 3 and 4. In like manner, the paper is refolded between rollers 4 and 5, and between 5 and 6 unless a paper deflector guide (not shown) is inserted at some point to cause paper to miss the slot between one pair of guide plates and pass instead directly through the next pair of rollers without being folded.

From the foregoing it is apparent that the rollers must be movable apart from one another. Rollers l and 2 must touch ever so slightly to handle a tissue paper without damaging it or leaving knurl marks thereon, but by the time the fourth fold is being made rollers 5 and 6 must be prepared .to part for sixteen thicknesses of paper (which may be heavy map paper as easily as tissue paper). And if a double thickness of a thick paper is fed initially between rollers 1 and 2, the last pair of rollers must part relatively much more than with this paper.

And yet the ratio of the pressure between rollers l't2 to the pressure between rollers 56 is maintained substantially constant for all weights of paper, both pressures being increased or decreased proportionately for different weights of paper. And changing the pressure exerted between a given pair of rollers, should not change the balance of pressure as between the two ends of a roller or affect the case of the roller in moving away from its adjoining roller as paper comes through. In accordance with the invention the rollers part without increasing the pressure significantly as they part, as commonly results with spring biased roller pressure controls.

In conventional folding machines, the power roller 2 is mounted in fixed bearings and does not move. But the other rollers are mounted at each end on a lever arm of length and configuration to afford convenient mounting within the space limitations present. Such mounting permits each end of each roller to move with respect to its neighbor to make space for paper to pass.

Thus, as seen in FIGURE 2 (wherein the gears are omitted for convenience of drawing), each end of roller 1 is mounted upon a lever 23 pivoted at 24. Each end of roller 2 is in fixed bearings. Each end of roller 3 is mounted upon a lever 25 pivotally mounted on the frame of the machine at 26. Each end of roller 4 is mounted upon a lever 27 pivotally mounted on the frame. of the machine at 28. Similarly, roller 5 is mounted upon lever 36 pivoted at 31 and roller 6 is mounted on lever 32 pivoted at 33.

referably the pivot points are so located, that roller 1 in moving away from roller 2, moves perpendicular to the tangent of the two rollers at their line of contact, as is true of rollers 3, 4, 5 and 6 (but not of roller 1) in FIGURE 2. Thus roller 3 moves away from roller 2 in a direction perpendicular to the tangent of the two rollers at their line of contact, and rollers 4, 5 and 6 likewise. With such an arrangement, the movement of roller 3 away from roller 2, for example, will have a minimum effect upon the contact between roller 3 and roller 4. Thus within the limits of actual roller movement experienced, the movement of one roller does not affect the pressure of or line of its contact with the next subsequent roller but to a minor extent.

In conventional folding machines, each of the levers 23, 25, 27, 3t} and 32 are independently spring biased to urge the respective rollers into contact with each other.

But in accordance with this invention, they are all hydraulically biased by a single hydraulic system. Thus there appears in FIGURE 2, hydraulic cylinder 35 adapted to bias lever 23, cylinder 36 adopted to bias lever 25, cylinder 37 adapted to bias lever 27, cylinder 38 adapted to bias lever 30 and cylinder 39 adapted to bias lever 32, each such hydraulic cylinder containing a piston which is connected by a piston rod to the appropriate lever.

A schematic of the entire hydraulic system appears in FIGURE 3. The hydraulic force is derived from a master cylinder 49. Cylinder 46 is fitted with a piston 4f adapted to have weights 42 remcvably mounted thereupon, so that by adding or removing weights 42 to the piston 41, the pressure in the hydraulic system can simply and quickly be changed in precise increments accurately predeterminable by the Weights 42.

Pressure created within the master cylinder 40 is transmitted to a center manifold 4-3. Mounted upon the center manifold is a pressure gage 44 and an accumulation chamber The accumulation chamber 45' may have a free piston or diaphragm (not shown) therein, if desired, to separate the hydraulic oil or other liquid from air preferably maintained in the dome of the accumulation chamber. The air in the accumulation chamber 45 operates to lessen the inertia of the system to small increments of movement of a roller, since the air yields quickly and easily to small increments of fluid pressure whereas the piston 41 with weights 42 yields less easily and more slowly due to their mass.

The air in the accumulation chamber 45 of course has a spring rate but the effect of this is dampened and removed by the yielding of the piston 41 and throttling of liquid through the orifices 54 hereinafter discussed.

Alternately, particularly in applications involving relatively little movement of the pistons in the biasing cyin-' ders, or a relatively large volume of air in the accumulation chamber which because of its volume has a small spring rate within the operating range, the cylinderpiston combination ill-41 can be eliminated and the air pressure alone used as the source of pressure for the hydraulic system.

Leading from the center manifold is a line 46 connected to a manifold 47 on the right hand side, and a line 48 connected to a manifold 49 on the left hand side of the machine.

The right hand manifold 47 is in communication through a line 50 to a hollow threaded mounting tube 51 which is in turn screwed into the top of a biasing cylinder 35 preferably having an orifice 54 therein, and having a piston 55 connected by a piston rod 56- to the lever 23.

In like manner, the right hand manifold is connected in communication with the other biasing cylinders on the right hand side of the machine, and the left hand manifold is connected in communication with the five biasing cylinders on the left hand side of the machine.

In applications where it is desired to have more pressure on the rollers making the later and hence heavier folds, this may be effected by proper choice of the size of the biasing cylinders for such rollers (taking care to use the same size biasing cylinder on each end of the same roller) or by using varying length lever arms for the difierent rollers.

The orifices 54 in the cylinders serve to dampen oscillations that occasionally occur, particularly when the machines are working rapidly on successive sheets of heavy paper.

FIGURE 4 illustrates an alternative to the FIGURE 3 biasing weights 42 for the master cylinder 40. In FIG- URE 4, the same cylinder 40 and piston 41 are used. But instead of the weights 42, a spring biasing device is used. The device comprises a bracket 6t? generally of L shape and adapted to be located on one side and the bottom of the cylinder 40. Hingedly secured to the top of the L bracket 60 is a lever 61 adapted to be positioned on top of the piston 41 so as to be able to urge the piston 41 downwardly. The other end of the lever 61 carries a hand operated adjustment screw 62, the rotation of which causes the screw 62 to move upward or downward in the lever 61. Between the screw 62 and the end of the base of the bracket 60 is positioned a tension spring 63. By turning the screw 62, the tension on the spring 63 is varied and thus the pressure in the hydraulic system and the pressure between all the pairs of rollers.

In such a system the spring rate and natural frequency of the spring 63 is chosen to be different from that of the air or gas in the accumulation chamber 4-5. This difference effects a dampening of the hydraulic system. If the master cylinder 4% is chosen to be of relatively large diameter so that in the operation of the system the piston 41 moves only slightly,- then the spring rate of the spring 63 within its range of operation may approximate Zero since the expansion or contraction of the spring in normal operation can be made very small in proportion to its length. And to the extent that the spring rate is involved, it influences the pressures between all pairs of rollers simultaneously and in the same amount, thus avoiding the awkward and time consuming multiple adjustments of machines with springs at each end of each roller.

In certain applications wherein high pressures are desired, a combination of the weights 42 and the spring 63 may be used to get large pressures with relatively light weight and With a spring operating within such a narrow range as to have a near zero effective spring ratio.

FIGURE 3 is also illustrative of a portion of the hydraulic system and its actual mounting on the folding machine. In that drawing there appears the master cylinder 49, center manifold, 43, lines 46 and 48 to the right hand and left hand manifolds 47 and 49 re spectively, and a line 50 connected to a threaded tube 51 which is mounted in a bracket 66 secured to the machine frame 67. Thus the cylinder itself is positioned by the threaded tube 51 which also carries the hydraulic fluid to the cylinder, and the location of the cylinder can be varied along a straight line by threading the tube 51 more or less through the bracket 66.

It sometime occurs that the nature of the gears '7 (see FIGURE 1) by which the master or power roller 2 drives the other rollers, creates in operation a thrust by which the gear ends of the rollers are urged away from each other. This circumstance upsets the delicate balance in pressures that is maintained between the two ends of a roller as an aid in obtaining evenly aligned feed of the paper and in avoiding feed of paper slightly misaligned so as to produce slightly misaligned folds.

The problem is rarely a major burden except as between the pull-in roller 1, and the power roller 2, for as paper is there fed it is positioned and held between only the single pair of rollers 1 and 2. By contrast, at the time paper is being folded between the rollers 2 and 3, it is still held and positioned between rollers 1 and 2; and when paper is being folded between rollers 3 and 4, it is still being held in proper alignment by the r01- lers 2-3.

Since the system of this invention contemplates equal force upon both ends of the roller as an inherent function of the hydraulic system described, in applications wherein this gear-thrust problem is bothersome, some means may be provided for adjusting relative pressures or bias as between the two ends of the pull-in roller 1 to restore the equality of pressure at both ends of the roller which is upset by the gear-produced thrust.

A slightly larger diameter biasing piston and cylinder might be used at the appropriate end of the pull-in roller, or the effective length of the lever arm 23 at one end or the other of the pull-in roller 1 might be made variable.

Alternately a separate manual adjustment as illustrated in FIGURE 3 may be used. The additional bias adjustment mechanism illustrated there takes the form of a thumb nut 64 and cooperating screw 65 mounted at each side of the machine. The screw 65 passes through a hole in the bracket 66 which bracket is secured, as by bolting or welding, to the machine frame 67.

Connected between the screws 65 and the levers 23 at each end of the roller 1, is a linkage 68 which is illustrated to be of resilient character. It is apparent that by adjustment on a thumb nut 64, the net effective force from the related biasing cylinder on the lever 23 can be partially cancelled, and by adjustments to one end or both, the gear-thrust imbalance can be compensated for, removing any tendency of the pull-in roller to misalign paper fed thereto.

While the linkage 68 is illustrated to include a spring, it has been found practical to use a heavy wire or small rod without a spring as such in the linkage, the heavy wire offering enough yield to render the fine adjustments here required easily made.

To the extent that this special adjustment to pull-in roller 1 is on occasion necessary in some machines for most efficient operation, the desirable object of a oneadjustment control for the entire machine is of course not accomplished. But by the combination of the hydraulic system with this manual supplementary control, the entire machine can be adjusted with at most three adjustments each of which work out to be much more easily and quickly made than any three of the ten adjustments required on machines with individual adjustment controls at each end of each roller as has been the uniform practice in the past. Moreover, once the manual adjustment of the thumb nuts 64 and screws 65 is made to compensate for the thrust under load of the particular gears of the machine, it is only uncommonly necessary to touch them again, the common adjustment being thereafter effected for the entire machine at the master cylinder 40 alone.

It might here be further noted that when direct spring biasing of each end of each roller is used, as is conventional in present day practice, the springs are selected for a more or less average paper. And such springs are too heavy and have too steep a spring rate for proper adjustment for and handling of thin papers such as tissue or onion skin. By contrast the hydraulic system is capable of being adjusted to the slightest pressures or the heaviest as easily as for the middle range and the spring rate, i.e., change in pressure with change in roller position, is zero in the FIGURE 3 embodiment, and can be made to approximate zero in the FIGURE 4 embodiment.

Folding machines are run at speeds up to something like 14,000 pieces per hour and frequently in a days operating time the temperature changes in the folding room and the rollers are enough to make significant differences in the operation. Particularly is this dramatized when a job is incomplete at days end, and when the machine is started again the next morning it is found to be badly out of adjustment. By contrast the single hydraulic system of FIGURE 4 controlling all rollers is not affected by temperature, and the FIGURE 5 embodiment is slightly affected only to a diminimus amount and in all events the machine is subject to a one-second readjustment by the hand adjustment screw 62 or the Weights 42.

Hydraulics have been used in some printing equipment, but not for the purposes or in the context here described and claimed, for in printing the paper is fed through rollers in a uniform stream of uniform thickness instead of hundreds of separate sheets per minute. And the pressure is not automatically adjusted in such printing devices, the required give being in the blanket that surfaces the roller opposite the type. Hydraulics are used in printing merely as a booster in moving the rollers apart by hand, and then the rollers are locked in position for the printing run, as distinguished from applicants loading of the hydraulic system so that it yields while still maintaining pressure on the rollers substantially constant regardless of their position. Moreover, applicant knows of no application of hydraulics even to printing wherein control of a plurality of rollers in a single hydraulic system is either desirable or taught for any purpose.

Modifications may be made in the invention as here in particularly described without departure from the scope of the invention. Accordingly, the foregoing description is to be construed as illustrative only and not as any limitation upon the invention as defined in the following claims.

What is claimed is:

1. In a paper folding machine having a train of a stationary roller and at least two movable rollers all disposed with axes parallelto each other and adapted to have paper passed first between a first of said rollers and a second of said rollers, and thence between the second of said rollers and the third of said rollers the combination comprising a plurality of lever means pivoted to the frame of said paper folding machine with each such lever means carrying one end of one of said movable rollers, first bias means comprising a hydraulic piston and cylinder combination for each such lever means, each such combination being adapted to bias said lever means in a direction by which pairs of said rollers are resiliently urged into contact with each other, additional bias means operable at at least one end of the first of said movable rollers independently of said hydraulic piston and cylinder combination, for making fine adjustments in the relative bias of the two ends of said first movable roller, hydraulic line means connected to each of said piston and cylinder combinations and to each other, a master hydraulic piston and cylinder combination connected to all said hydraulic line means, means for resiliently urging said master piston into said master cylinder with a predetermined and yieldable force whereby a pressure of predetermined amount is created within all said lines and cylinders and said levers are biased in response thereto.

2. The invention defined in claim 1 characterized by the addition of an accumulation chamber connected to said hydraulic line means and having gas trapped therein.

3. The invention defined in claim 1 characterized by the addition into each system composed of such biasing cylinder means and its appurtenant hydraulic line means,

of an orifice adapted to offer some resistance to flow of hydraulic fluid therethrough.

4. The invention of claim 2 characterized by the addition into each system composed of such biasing cylinder means and its appurtenant hydraulic line means, of an orifice adapted to offer some resistance to flow of hydraulic fluid therethrough.

5. The invention defined in claim 1 wherein the piston of said master hydraulic piston and cylinder combination is adapted to move vertically and said means for resiliently urging said master piston into said master cylinder is a weight carried by said master piston in combination with a spring.

6. In a paper folding machine having a train of a stationary roller and at least two movable rollers all disposed with axes parallel to each other and adapted for having paper passed between pairs thereof, the combination comprising a plurality of lever means pivoted to the frame of said paper folding machine with each lever means carrying one end of one of said movable rollers, a hydraulic piston and cylinder combination for each such lever means, each such combination being adapted to bias said lever means in a direction by which pairs of said rollers are resiliently urged into contact with each other, hydraulic line means connected to each of said piston and cylinder combinations and to each other, a master hydraulic piston and cylinder combination connected to all said hydraulic line means, means for resiliently urging said master piston into said master cylinder with a predetermined and yieldable force whereby a pressure of predetermined amount is created within all said lines and cylinders and said levers are biased in response thereto.

7. The invention of claim 6 characterized by the addition of an accumulation chamber connected to said hydraulic line means and having gas trapped therein.

8. The invention of claim 6 characterized by the addition into each such biasing cylinder means and its appurtenant hydraulic line means, of an orifice adapted to offer some resistance to flow of hydraulic fluid therethrough.

9. The invention of claim 7 characterized by the addition into each such biasing cylinder means and its appurtenant hydraulic line means, of an orifice adapted to offer some resistance to flow of hydraulic fluid therethrough.

10. The invention defined in claim 6 wherein the piston of said master hydraulic piston and cylinder combination is adapted to move vertically and said means for resiliently urging said master piston into said master cylinder is a weight carried by said master piston in combination with a spring.

11. The invention defined in claim 6 wherein said means for resiliently urging said master piston into said master cylinder with a predetermined and yieldable force is a spring.

12. In a paper folding machine having a train of rollers including a stationary roller and at least two movable rollers all disposed adjacent and with axes parallel to each other and adapted for having paper passed between pairs thereof, the combination comprising a plurality of levers means pivoted to the frame of the folding machine, each of said lever means carrying a different end of a different one of said movable rollers, first biasing means comprising a hydraulic piston and cylinder combination for each such lever means, each such combination biasing said lever means in a direction such that pairs of said rollers are resiliently urged into contact with each other, second biasing means operable on at least one end of the first of said movable rollers independently of said hydraulic piston and cylinder combination for making fine adjustments in the relative bias of the two ends of said first movable roller, conduit means interconnecting all of said hydraulic piston and cylinder combinations, means for generating hydraulic pressure in all of said hydraulic piston and cylinder combinations, said pressure generating means comprising a chamber for enclosing a pressure generating medium, and means for adjustably and resiliently applying said pressure in each of said hydraulic piston and cylinder combinations.

13. In a paper folding machine having a train of a stationary roller and at least two movable rollers all disposed with axes parallel to each other and adapted to have foldable sheets passed between pairs thereof, the combination comprising a plurality of lever means pivoted to the frame of said folding machine with each such lever means carrying an end of one of said movable rollers, a biasing means comprising a piston and cylinder combination for each of the lever means carrying corresponding ends of said movable rollers, each said combination being adapted to bias a said lever means in a direction such that pairs of said rollers are yieldably urged into contact with each other, and a common source of fluid pressure operatively connected to and adapted to apply a predetermined equal yieldable force to all said piston and cylinder combinations for all the lever means carrying said corresponding ends of said movable rollers, whereby a pressure of predetermined amount is applied within .the cylinders and the levers are biased in response thereto to yieldably urge pairs of said movable rollers into contact with each other at said corresponding ends.

14. In a paper folding machine having a train of a stationary roller and at least two movable rollers all disposed with axes parallel to each other and adapted 30 for having foldable sheets passed between pairs thereof, the combination comprising a plurality of lever means pivoted to the frame of said paper folding machine for movably supporting ends of said movable rollers, an end of one movable roller being carried by one said lever means and the corresponding end of each other movable roller being carried by another of said lever means, a biasing means comprising a reciprocable fluid pressure actuated element for each of said lever means, each such element being operatively connected with and adapted to bias a said lever means in a direction such that corresponding ends of pairs of said rollers are yieldably urged into contact with each other, and a common source of fluid pressure including a confined fluid pressure enclosure filled with fluid under a predetermined adjustable pressure and connected to all said biasing means for simultaneously actuating all of said elements with a predetermined equal and yieldable force whereby a pressure of predetermined amount is applied to all said biasing means and said lever means are biased in response thereto.

15. A paper folding machine as defined in claim 14 wherein the other ends of said movable rollers are similarly supported by a plurality of lever means and similarly simultaneously and adjustably biased by biasing means activated by said common source of fluid under pressure.

References (Iited in the file of this patent UNITED STATES PATENTS 1,843,763 Davidson Feb. 2, 1932 FOREIGN PATENTS 423,066 Italy Sept. 9, 1947 

1. IN A PAPER FOLDING MACHINE HAVING A TRAIN OF A STATIONARY ROLLER AND AT LEAST TWO MOVABLE ROLLERS ALL DISPOSED WITH AXES PARALLEL TO EACH OTHER AND ADAPTED TO HAVE PAPER PASSED FIRST BETWEEN A FIRST OF SAID ROLLERS AND A SECOND OF SAID ROLLERS, THENCE BETWEEN THE SECOND OF SAID ROLLERS AND THE THIRD OF SAID ROLLERS THE COMBINATION COMPRISING A PLURALITY OF LEVER MEANS PIVOTED TO THE FRAME OF SAID PAPER FOLDING MACHINE WITH EACH SUCH LEVER MEANS CARRYING ONE END OF ONE SAID MOVABLE ROLLERS, FIRST BIAS MEANS COMPRISING A HYDRAULIC PISTON AND CYLINDER COMBINATION FOR EACH SUCH LEVER MEANS, EACH SUCH COMBINATION BEING ADAPTED TO BIAS SAID LEVER MEANS IN A DIRECTION BY WHICH PAIRS OF SAID ROLLERS ARE RESILIENTLY URGED INTO CONTACT WITH EACH OTHER, ADDITIONAL BIAS MEANS OPERABLE AT AT LEAST ONE END OF THE FIRST OF SAID MOVABLE ROLLERS INDEPENDENTLY OF SAID HYDRAULIC PISTON AND CYLINDER COMBINATION, FOR MAKING FINE ADJUSTMENTS IN THE RELATIVE BIAS OF THE TWO ENDS OF SAID FIRST MOVABLE ROLLER, HYDRAULIC LINE MEANS CONNECTED TO EACH OF SAID PISTON AND CYLINDER COMBINATIONS AND TO EACH OTHER, A MASTER HYDRAULIC PISTON AND CYLINDER COMBINATION CONNECTED TO ALL SAID HYDRAULIC LINE MEANS, MEANS FOR RESILIENTLY URGING SAID MASTER PISTON INTO SAID MASTER CYLINDER WITH A PREDETERMINED AND YIELDABLE FORCE WHEREBY A PRESSURE OF PREDETERMINED AMOUNT IS CREATED WITHIN ALL SAID LINES AND CYLINDERS AND SAID LEVERS ARE BIASED IN RESPONSE THERETO. 